1. Field of the Invention
This invention relates to apparatus for engaging a cargo pallet and more particularly to such apparatus useful for engaging a pallet for slidably pulling the pallet over a surface.
2. Description of the Prior Art
In unloading palletized loads from transport vehicles at sites lacking a surface level with the bed of the transport vehicle, it is necessary that the pallets be slid or pulled on the vehicle bed surface to a point sufficiently close to the door of the vehicle that a fork lift truck can pick up the pallet. Because of the substantial weight of a typical palletized load, the frictional force between the pallet and the vehicle bed surface is such that power equipment is needed to slide the pallet to a point near the vehicle door. It is necessary that some means be provided for permitting the power equipment to engage the pallet, and numerous engaging means are disclosed in the prior art.
One form of engaging means has teeth which dig into the pallet stringer to afford a grip thereon. The pallet puller disclosed in U.S. Pat. No. 3,807,786 exemplifies this form of gripping device. Such gripping device can damage the pallet by breaking the wood members of which it is formed and can become inadvertently disengaged from the pallet during a pulling operation.
Another form of pallet engaging device includes a hook adapted to engage the foot boards that form the bottom of the pallet. Such hook devices are disclosed in U.S. Pat. Nos. 3,073,613; 3,727,966; 4,094,544 and 4,114,941. These hook devices are less likely to subject the pallet to damage but are prone to disengage from the pallet, particularly when tension on a chain or cable extending from the engaging means to the vehicle is temporarily interrupted.